In short:
An ex-SAS officer who escorted an accused crime boss back to Sydney has become uncontactable days before he is due to give evidence, according to court documents.
Masood Zakaria, 33, was deported from Türkiye in 2023 after police issued a warrant for his arrest, but his lawyers argue the extradition was unlawful.
What's next?
The court is expected to hear from multiple witnesses, including Australian Federal Police Commissioner Krissy Barrett.
An ex-SAS officer involved in an accused Sydney gangster's contested extradition to Australia is uncontactable, days before he is due to give evidence, a court has been told.
Alleged Alameddine crime family boss Masood Zakaria claims in court documents former soldier Nathan Heckel is a key witness, in his attempt to have murder charges dismissed.
Mr Zakaria was charged with the 2021 murders of Salim and Toufik Hamzy and was later apprehended in Türkiye in 2023.
Mr Zakaria's lawyers have previously compared his ensuing deportation back to Australia as a "kidnapping" and are asking the court to permanently stay his charges.
If successful, it could be the first time in New South Wales someone accused of murder has walked free due to a stay application brought on after alleged unlawful actions by law enforcement.
AFP's $1m payment to contractor
Mr Heckel's connection to the case came to light in documents filed by Mr Zakaria's legal team last month after it emerged he was one of several private contractors from security company Hart International the Australian Federal Police (AFP) hired to escort Mr Zakaria to Sydney.
The Cyprus-based firm is part of a UK conglomerate of companies with a regional office in Sydney founded by former British SAS officer Lord Richard Westbury, who is not involved in the case.
The court documents said not long after attempts to reach Mr Heckel to give evidence were made, online profiles connected to him vanished.
Documents filed by Mr Zakaria said in further attempts to contact Mr Heckel, a process server who was sent to Mr Heckel's address was informed he may be in Iraq on business.
In court last month, Mr Zakaria's lawyers said Mr Heckel was one of several people they alleged "kidnapped" him, who they were yet to locate.
The accused Sydney gangster claims the group picked him up at a Turkish airport and flew him back to Australia after Türkiye deported him.
The court was previously told the group took photographs of Mr Zakaria handcuffed on a plane and sent it back to the AFP.
In total, the AFP paid more than $1 million to Hart International to have Mr Zakaria brought back from Istanbul.
AFP boss quizzed over use of private security firms
The case, scheduled to begin this week, is set to hear from some of the most senior crime fighters in Australia about what they knew about Mr Zakaria's deportation to Sydney.
AFP Commissioner Krissy Barrett, her predecessor Reece Kershaw and NSW Police's Jason Weinstein and Grant Taylor are expected to be called as witnesses.
Documents tended in the case also showed how AFP officers celebrated Mr Zakaria's return to Australia in messages with their Turkish counterparts.
Other messages in court documents detailed the AFP officers' fear of "anything shonky" being done by local police who arrested him in the quiet Turkish town of Muğla in January 2023.
An AFP spokesperson declined to comment on Mr Heckel's role in the matter when contacted by the ABC.
When asked on 702 ABC Sydney earlier this month about whether using private security firms was a regular approach, Commissioner Barrett lauded the agency's relationships with foreign law enforcement.
"So we predominantly work with our law enforcement partners, and there are a number of examples where we have been able to extradite high-value targets back to Australia and put them before the courts,"she said.
"But also examples of where local law enforcement offshore have been able to take local action, which has had a disruptive impact on someone that's been having a very high impact on Australia."
Commissioner Barrett added: "We need to remember that these are high-value targets that are not just having an impact on our country, they're having an impact on a number of countries, including usually the country that they're living or residing in."

